U.S. patent application number 11/227866 was filed with the patent office on 2007-03-15 for thermosetting coating compositions with multiple cure mechanisms.
This patent application is currently assigned to BASF Corporation. Invention is credited to Sunitha Grandhee, Swaminathan Ramesh.
Application Number | 20070059532 11/227866 |
Document ID | / |
Family ID | 37440775 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070059532 |
Kind Code |
A1 |
Ramesh; Swaminathan ; et
al. |
March 15, 2007 |
Thermosetting coating compositions with multiple cure
mechanisms
Abstract
A curable coating composition comprises (a) a compound having
two types of functionality, functionality A and functionality B,
that react in curing the coating, (b) a second material having
functionality C that reacts with functionality A in curing the
coating, and (c) a crosslinker having a plurality of functional
groups D that react at least with functionality B in curing the
coating. Functional groups D may also react with functionality C
and/or with a functional group formed as a result of the reaction
of functionality C with functionality A. The curable coating
composition is applied to a substrate and cured under conditions
appropriate for reactions of the functionalities A, B, C, and
D.
Inventors: |
Ramesh; Swaminathan;
(Canton, MI) ; Grandhee; Sunitha; (Novi,
MI) |
Correspondence
Address: |
BASF CORPORATION
1609 BIDDLE AVENUE
MAIN BUILDING
WYANDOTTE
MI
48192
US
|
Assignee: |
BASF Corporation
Southfield
MI
|
Family ID: |
37440775 |
Appl. No.: |
11/227866 |
Filed: |
September 15, 2005 |
Current U.S.
Class: |
428/423.1 ;
528/44 |
Current CPC
Class: |
C09D 175/16 20130101;
C08G 18/3831 20130101; C08G 18/718 20130101; C08G 18/3234 20130101;
Y10T 428/31551 20150401; C08G 18/792 20130101; C08G 18/728
20130101; C08G 18/672 20130101; C09D 175/12 20130101; C09D 201/025
20130101 |
Class at
Publication: |
428/423.1 ;
528/044 |
International
Class: |
C08G 18/00 20060101
C08G018/00 |
Claims
1. A curable coating composition, comprising: (a) a compound having
functionality A and functionality B that react in curing the
coating, (b) a second material having functionality C that reacts
with functionality A in curing the coating, and (c) a crosslinker
having a plurality of functional groups D that react at least with
functionality B in curing the coating.
2. A curable coating composition according to claim 1, wherein the
crosslinker with functional groups D also reacts with a functional
group formed as a result of the reaction of functionality C with
functionality A.
3. A curable coating composition according to claim 1, wherein
compound (a) has a plurality of groups of at least one of
functionality A or functionality B.
4. A curable coating composition according to claim 1, wherein
material (b) is an oligomer or a polymer.
5. A curable coating composition according to claim 4, wherein
material (b) has a plurality of groups of functionality C.
6. A curable coating composition according to claim 4, wherein
material (b) is selected from the group consisting of acrylic
polymers, polyurethane polymers, polyester polymers, star
polyesters, epoxies, and combinations of these.
7. A curable coating composition according to claim 1, wherein
material (b) is a compound having at least two groups of
functionality C.
8. A curable coating composition according to claim 1, wherein
crosslinker (c) has at least two functional groups D.
9. A curable coating composition according to claim 1, wherein
compound (a) has carboxylic acid and carbamate functionality,
material (b) has epoxide functionality, and crosslinker (c)
comprises an aminoplast crosslinker.
10. A curable coating composition according to claim 1, wherein
compound (a) has isocyanate functionality and silyl ether
functionality, material (b) has primary and/or secondary amine
functionality, and crosslinker (c) has hydroxyl functionality.
11. A curable coating composition according to claim 1, wherein
compound (a) has isocyanate functionality and silyl ether
functionality, material (b) has secondary hydroxyl functionality,
and crosslinker (c) has primary hydroxyl functionality.
12. A curable coating composition according to claim 1, wherein
compound (a) has hydroxyl functionality and silyl ether
functionality, material (b) has isocyanate functionality, and
crosslinker (c) has hydroxyl functionality.
13. A curable coating composition according to claim 1, wherein
compound (a) has epoxide functionality and carbamate functionality,
material (b) has carboxylic acid functionality, and crosslinker (c)
is an aminoplast crosslinker.
14. A curable coating composition according to claim 1, wherein
compound (a) has alkoxyalkyl amine and carbamate functionality,
material (b) has hydroxyl functionality, and crosslinker (c) is an
aminoplast crosslinker.
15. A curable coating composition according to claim 1, wherein
compound (a) has isocyanate and carbamate functionality, material
(b) has hydroxyl functionality, and crosslinker (c) is an
aminoplast crosslinker.
16. A curable coating composition according to claim 1, wherein
compound (a) has isocyanate functionality and ethylenic
unsaturation, material (b) has hydroxyl functionality, and
crosslinker (c) is an ethylenically unsaturated crosslinker, and
further wherein the composition includes a photocatalyst.
17. A method of coating a substrate, comprising steps of applying a
layer of a curable coating composition according to claim 1 to the
substrate and curing the applied coating layer.
18. A coated substrate prepared according to the method of claim
17.
19. A method of coating a substrate according to claim 17, wherein
in the step of curing the applied coating layer, curing conditions
are adjusted to promote substantially sequential reactions of one
of the functionalities of compound (a).
20. A coated substrate prepared according to the method of claim
19.
Description
FIELD OF THE INVENTION
[0001] The invention relates to thermosetting coating compositions,
materials therefor, and methods of making and using such coatings
compositions.
BACKGROUND OF THE INVENTION
[0002] Curable, or thermosettable, coating compositions are widely
used in the coatings art, particularly for topcoats in the
automotive and industrial coatings industry. Color-plus-clear
composite coatings provide topcoats with exceptional gloss, depth
of color, distinctness of image, and special metallic effects. The
automotive industry has made extensive use of these coatings for
automotive body panels. A topcoat coating should be durable to
maintain its appearance and provide protection under service
conditions during the lifetime of the coated article. Topcoat
coatings for automotive vehicles, for example, are typically
exposed to all kinds of weather, ultraviolet rays from the sun,
abrasions from gravel thrown up during driving or from items set on
the car when parked, and other conditions that can degrade the
coating. For some time, researchers have directed their efforts to
providing coatings with greater resistance to environmental etch.
"Environmental etch" is a term applied to a kind of exposure
degradation that is characterized by spots or marks on or in the
finish of the coating that often cannot be rubbed out.
[0003] Curable coating compositions utilizing carbamate-functional
resins are described, for example, in U.S. Pat. Nos. 5,693,724,
5,693,723, 5,639,828, 5,512,639, 5,508,379, 5,451,656, 5,356,669,
5,336,566, and 5,532,061, each of which is incorporated herein by
reference. These coating compositions can provide significant
improvements in resistance to environmental etch over other coating
compositions, such as hydroxy-functional acrylic/melamine coating
compositions. On the other hand, carbamate-functional resins tend
to require more organic solvent to achieve acceptable viscosity for
application and leveling of the applied film to obtain desired
smoothness. Coatings with higher amounts of organic solvent produce
more regulated emissions during application. Coatings with
hydroxyl-functional acrylic polymers cured using blocked
polyisocyanate can also provide excellent resistance to
environmental etch in cured coatings, but these coatings do not
have the desired scratch and mar resistance. Coatings with
hydroxyl-functional acrylic polymers cured using aminoplasts can be
formulated at higher solids and cured at lower temperatures
relative to the other compositions mentioned, but do not provide
the environmental etch resistance or scratch and mar resistance of
the other coatings. Other coating chemistries have been used, but
these also have shortcomings, such as poor weathering properties or
high volatile organic content [VOC].
[0004] It would be advantageous to have a coating composition that
could provide desired environmental etch resistance and improved
scratch and mar resistance without dramatically increasing the
viscosity of the coating composition.
SUMMARY OF THE INVENTION
[0005] The present invention provides a curable coating composition
comprising (a) a compound having two types of functionality,
functionality A and functionality B, that react in curing the
coating, (b) a second material having functionality C that reacts
with functionality A in curing the coating, and (c) a crosslinker
having a plurality of functional groups D that react at least with
functionality B in curing the coating. Functional groups D may also
react with functionality C and/or with a functional group formed as
a result of the reaction of functionality C with functionality A.
The curable coating composition is applied to a substrate and cured
under conditions appropriate for reactions of the functionalities
A, B, C, and D. The conditions may be adjusted for the cure or
during the cure to promote sequential reactions (that is, reaction
of one of functionalities A or B substantially prior to the other).
Depending on the reactivities of the functional groups, some of
them may be blocked to reduce viscosity build up during storage as
well as to control the direction of reaction during cure.
[0006] As used in this description of the present invention,
"compound" is used to refer to a material that is monomeric; i.e.,
a material that is not an oligomer or a polymer. "Material" is used
in a more general sense to include compounds, oligomers, and
polymers.
[0007] In one embodiment, the curable coating composition comprises
(a) a compound having carboxylic acid and carbamate functionality,
(b) a material having epoxide functionality, and (c) an aminoplast
crosslinker.
[0008] In a second embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and silyl
ether functionality, (b) a material having primary and/or secondary
amine functionality, and (c) a hydroxyl-functional crosslinker.
[0009] In a third embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and silyl
ether functionality, (b) a material having secondary hydroxyl
functionality, and (c) a crosslinker having primary hydroxyl
functionality.
[0010] In a fourth embodiment, the curable coating composition
comprises (a) a compound having hydroxyl functionality and silyl
ether functionality, (b) a material having isocyanate
functionality, and (c) a hydroxyl-functional crosslinker.
[0011] In a fifth embodiment, the curable coating composition
comprises (a) a compound having epoxide functionality and carbamate
functionality, (b) a material having carboxylic acid functionality,
and (c) an aminoplast crosslinker.
[0012] In a sixth embodiment, the curable coating composition
comprises (a) a compound having alkoxyalkyl amino functionality and
carbamate functionality, (b) a material having hydroxyl
functionality, and (c) an aminoplast crosslinker.
[0013] In a seventh embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and
carbamate functionality, (b) a material having hydroxyl
functionality, and (c) an aminoplast crosslinker.
[0014] In an eighth embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and
ethylenic unsaturation, (b) a material having hydroxyl
functionality, and (c) an ethylenically unsaturated crosslinker
with a photocatalyst. This composition cures with heat and actinic
radiation.
[0015] An aminoplast for purposes of the invention is a material
obtained by reaction of an activated nitrogen with a lower
molecular weight aldehyde forming an alkylol group, optionally
further reacted with an alcohol (preferably a mono-alcohol with one
to four carbon atoms) to form an ether group.
[0016] A carbamate group has a structure ##STR1## in which R is H
or alkyl. Preferably, R is H or alkyl of from 1 to about 4 carbon
atoms, and more preferably R is H.
[0017] The invention also provides a method of coating a substrate
including steps of applying a coating composition of the invention
and curing the applied layer of coating composition and a coated
substrate formed by the method.
[0018] "A" and "an" as used herein indicate "at least one" of the
item is present; a plurality of such items may be present, when
possible. "About" when applied to values indicates that the
calculation or the measurement allows some slight imprecision in
the value (with some approach to exactness in the value;
approximately or reasonably close to the value; nearly). If, for
some reason, the imprecision provided by "about" is not otherwise
understood in the art with this ordinary meaning, then "about" as
used herein indicates a possible variation of up to 5% in the
value.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The following description of the preferred embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0020] The curable coating composition comprises (a) a compound
having functionality A and functionality B that react in curing the
coating, (b) a second material having functionality C that reacts
with functionality A in curing the coating, and (c) a crosslinker
having a plurality of functional groups D that react at least with
functionality B in curing the coating. Functional groups D may also
react with functionality C and/or with a functional group formed as
a result of the reaction of functionality C with functionality
A.
[0021] Compound (a) has at least one group of functionality A and
at least one group of functionality B, but may have a plurality of
groups of functionality A and/or functionality B. Compound (a) may
be formed in general by using a starting compound having one of the
functionalities and partially converting that functionality to the
other functionality or by reacting a starting compound with a
combination of a compound that provides one functionality and a
compound that provides the other functionality. If the two
functionalities are reactive with one another, then one of the
functionalities must be protected with a blocking group.
[0022] Material (b) may be a compound, an oligomer, or a polymer. A
compound having the desired functionality C may be commercially
available, or it may be prepared by reaction of a first compound
with a second compound that produces the desired functionality C.
When material (b) is a compound, it has preferably at least 2, more
preferably from 2 to about 20, even more preferably from 2 to about
8, and still in one embodiment more preferably from about 2 to
about 4, and in another embodiment preferably 3 functional groups
C. An oligomer or polymer having the desired functionality C may be
prepared by polymerization of a monomer having the desired
functional group C or by adducting the polymer or oligomer after
polymerization to produce functional groups C. For example and
without limitation, polymerized materials (b) may be acrylic
polymers, polyurethane polymers, polyester polymers, star
polyesters, epoxies, and polyethers.
[0023] Crosslinker (c) should have a plurality of functional groups
D. Crosslinker (c) has preferably from 2 to 20, more preferably
from 2 to 8, still more preferably from 2 to 6, and even more
preferably from 2 to 4 functional groups D available for reaction
with compound (a).
[0024] The curable coating composition may be applied in a coating
layer to a substrate and then cured. The curing conditions are
appropriate for reaction of the functional groups A, B, C, and D.
The curing conditions are adjusted to promote substantially
sequential reactions of one of the functionalities of compound (a),
so that at the beginning of cure only one of the functionalities is
reacting. The applied coating layer is cured to produce a coated
substrate.
[0025] In one embodiment, the curable coating composition comprises
(a) a compound having carboxylic acid and carbamate functionality,
(b) a material having epoxide functionality, and (c) an aminoplast
crosslinker.
[0026] In this embodiment, the compound (a) has carboxylic acid and
carbamate groups. The compound having acid and carbamate groups may
have one acid group per 0.5 to 1.5 carbamate groups, on average,
but it is preferred that the compound have substantially about the
same acid equivalent weight and carbamate equivalent weight. The
compound preferably is monomeric and has at least a molecular
weight of 119 and up to about 40 carbon atoms. In certain
embodiments, the compound has one carbamate group and one acid
group, but in other embodiments the compound has more than one
carbamate group, more than one acid group, or more than one acid
group and more than one carbamate group. In particular, the
compound having acid and carbamate groups may be a reaction product
of a carboxylic acid anhydride compound and a hydroxyalkyl
carbamate. Examples of suitable anhydrides compounds include,
without limitation, phthalic anhydride, tetrahydrophthalic
anhydride, succinic anhydride, glutaric anhydride, dimethyl
succinic anhydride, maleic anhydride, trimellitic anhydride,
pyromellitic anhydride, hexahydrophthalic anhydride, and
methyl,hexahydrophthalic anhydride. Examples of suitable
hydroxyalkyl carbamate compounds include, without limitation,
hydroxyethyl carbamate, hydroxypropyl carbamate, hydroxybutyl
carbamate, and a beta-hydroxy carbamate compound derived from
glycidyl carbonate ester of neodecanoic acid and ammonia. The ring
opening reaction of an anhydride and the hydroxy, carbamate leads
to a monomer with at least one carboxylic acid and one carbamate
group.
[0027] The material (b) having epoxide functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of epoxide groups. Examples of compounds having epoxide
functionality include, without limitation, epoxide ethers of
alcohols and polyols and epoxide esters of monocarboxylic acids,
polycarboxylic acids, and polyacrylic polymers made with glycidyl
methacrylate or other glycidyl-functional, addition polymerizable
monomers.
[0028] Examples of suitable oligomers having epoxide functionality
are bisphenol diglycidyl ethers, trimethylolpropane triglycidyl
ether, pentaerythritol tetraglycidyl ethers, and
triglycidylisocyanurate (also known as TGIC). Examples of suitable
polymers include, without limitation, epoxide-functional acrylic
polymers, epoxide-functional polyester polymers, and epoxide
functional polyurethanes. The epoxide-functional polymer preferably
has an epoxide equivalent weight from about 300 to about 1500.
[0029] The acrylic polymer may be produced by copolymerizing an
appropriate amount of a glycidyl-group monomer(s), for example by
copolymerizing one or more of the monomers glycidyl acrylate,
glycidyl methacrylate, or allyl glycidyl ether. The polyester or
polyurethane with epoxide functionality may be produced by reacting
a polyester or polyurethane with hydroxyl or acid functionality
with epichlorohydrin. The acrylic polymers may be polymerized using
one or more further comonomers. Examples of such comonomers
include, without limitation, esters of .alpha.,.beta.-ethylenically
unsaturated monocarboxylic acids containing 3 to 5 carbon atoms
such as acrylic, methacrylic, and crotonic acids and of
.alpha.,.beta.-ethylenically unsaturated dicarboxylic acids
containing 4 to 6 carbon atoms; vinyl esters, vinyl ethers, vinyl
ketones, and aromatic or heterocyclic aliphatic vinyl compounds.
Representative examples of suitable esters of acrylic, methacrylic,
and crotonic acids include, without limitation, those esters from
reaction with saturated aliphatic and cycloaliphatic alcohols
containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl,
isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, lauryl,
stearyl, cyclohexyl, trimethylcyclohexyl, tetrahydrofurfuryl,
stearyl, sulfoethyl, and isobornyl acrylates, methacrylates, and
crotonates. Representative examples of other ethylenically
unsaturated polymerizable monomers include, without limitation,
such compounds as dialkyl fumaric, maleic, and itaconic esters,
prepared with alcohols such as methanol, ethanol, propanol,
isopropanol, butanol, isobutanol, and tert-butanol. Representative
examples of co-polymerizable vinyl monomers include, without
limitation, such compounds as vinyl acetate, vinyl propionate,
vinyl ethers such as vinyl ethyl ether, vinyl and vinylidene
halides, and vinyl ethyl ketone. Representative examples of
aromatic or heterocyclic aliphatic vinyl compounds include, without
limitation, such compounds as styrene, .alpha.-methyl styrene,
vinyl toluene, tert-butyl styrene, and 2-vinyl pyrrolidone. The
comonomers may be used in any combination. Monomers that are
reactive with epoxide groups under the polymerization conditions
should be avoided.
[0030] The acrylic polymers may be prepared using conventional
techniques, such as by heating the monomers in the presence of a
polymerization initiating agent and optionally chain transfer
agents. The polymerization is preferably carried out in solution,
although it is also possible to polymerize the acrylic polymer in
bulk. Suitable polymerization solvents include, without limitation,
esters, ketones, ethylene glycol monoalkyl ethers and propylene
glycol monoalkyl ethers, alcohols, and aromatic hydrocarbons.
[0031] Typical initiators are organic peroxides such as dialkyl
peroxides such as di-t-butyl peroxide, peroxyesters such as t-butyl
peroctoate and t-butyl peracetate, peroxydicarbonates, diacyl
peroxides, hydroperoxides such as t-butyl hydroperoxide, and
peroxyketals; azo compounds such as
2,2'azobis(2-methylbutanenitrile) and
1,1'-azobis(cyclohexanecarbonitrile); and combinations of these.
Typical chain transfer agents are mercaptans such as octyl
mercaptan, n- or tert-dodecyl mercaptan; halogenated compounds,
thiosalicylic acid, mercaptoacetic acid, mercaptoethanol, and
dimeric alpha-methyl styrene.
[0032] The solvent or solvent mixture is generally heated to the
reaction temperature and the monomers and initiator(s) and
optionally chain transfer agent(s) are added at a controlled rate
over a period of time, typically from about two to about six hours.
The polymerization reaction is usually carried out at temperatures
from about 20.degree. C. to about 200.degree. C. The reaction may
conveniently be done at the temperature at which the solvent or
solvent mixture refluxes, although with proper control a
temperature below the reflux may be maintained. The initiator
should be chosen to match the temperature at which the reaction is
carried out, so that the half-life of the initiator at that
temperature should preferably be no more than about thirty minutes,
more preferably no more than about five minutes. Additional solvent
may be added concurrently. The mixture is usually held at the
reaction temperature after the additions are completed for a period
of time to complete the polymerization. Optionally, additional
initiator may be added to ensure complete conversion of monomers to
polymer.
[0033] The acrylic, polyester, and polyurethane polymers should
have a weight average molecular weight of at least about 500,
preferably at least about 3000, more preferably at least about
3500, and particularly preferably at least about 4000. Weight
average molecular weight may be determined by gel permeation
chromatography using polystyrene standard. In addition, the weight
average molecular weight is preferably up to about 7000, more
preferably up to about 5000, and still more preferably up to about
4500.
[0034] While a wide range of weight ratios are possible for
formulating with the combinations of materials (a), (b), and (c),
certain embodiments may include from about 1 to about 10 parts by
weight of material (a), from about 3 to about 20 parts by weight of
material (b), and from about 0.5 to about 3 parts by weight of
material (c), The ratios may be adjusted based on the equivalent
weights of the individual materials and the extent to which it is
desired for the reactions to proceed, as well as the degree of cure
desired. The composition may further include a fatty acid material
for increased flexibility of the cured paint film.
[0035] The coating composition of the first embodiment also
includes an aminoplast as a crosslinker. An aminoplast for purposes
of the invention is a material obtained by reaction of an activated
nitrogen with a lower molecular weight aldehyde, optionally further
reacted with an alcohol (preferably a mono-alcohol with one to four
carbon atoms) to form an ether group. Preferred examples of
activated nitrogens are activated amines such as melamine,
benzoguanamine, cyclohexylcarboguanamine, and acetoguanamine;
ureas, including urea itself, thiourea, ethyleneurea,
dihydroxyethyleneurea, and guanylurea; glycoluril; amides, such as
dicyandiamide; and carbamate functional compounds having at least
one primary carbamate group or at least two secondary carbamate
groups.
[0036] The activated nitrogen is reacted with a lower molecular
weight aldehyde. The aldehyde may be selected from formaldehyde,
acetaldehyde, crotonaldehyde, benzaldehyde, or other aldehydes used
in making aminoplast resins, although formaldehyde and
acetaldehyde, especially formaldehyde, are preferred. The activated
nitrogen groups are at least partially alkylolated with the
aldehyde, and may be fully alkylolated; preferably, the activated
nitrogen groups are fully alkylolated. The reaction may be
catalyzed by an acid, e.g. as taught in U.S. Pat. No. 3,082,180,
the contents of which are incorporated herein by reference.
[0037] The alkylol groups formed by the reaction of the activated
nitrogen with aldehyde may be partially or fully etherified with
one or more monofunctional alcohols. Suitable examples of the
monofunctional alcohols include, without limitation, methanol,
ethanol, propanol, isopropanol, butanol, isobutanol, tert-butyl
alcohol, benzyl alcohol, and so on. Monofunctional alcohols having
one to four carbon atoms and mixtures of these are preferred. The
etherification may be carried out, for example, by the processes
disclosed in U.S. Pat. Nos. 4,105,708 and 4,293,692, the
disclosures of which are incorporated herein by reference.
[0038] It is preferred for the aminoplast to be at least partially
etherified, and especially preferred for the aminoplast to be fully
etherified. The preferred compounds have a plurality of methylol
and/or etherified methylol groups, which may be present in any
combination and along with unsubstituted nitrogen hydrogens. Fully
etherified melamine-formaldehyde resins are particularly preferred,
for example and without limitation hexamethoxymethyl melamine.
[0039] In a second embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and silyl
ether functionality, (b) a material having primary and/or secondary
amine functionality, and (c) a hydroxyl-functional crosslinker.
[0040] The compound (a) having isocyanate functionality and ether
functionality may be, for example,
isocyanatopropyltrimethoxysilane.
[0041] The material (b) having primary and/or secondary amine
functionality may be a compound, an oligomer, or a polymer having
at least one, preferably a plurality of such amine groups having
active hydrogens. Examples of compounds having primary and/or
secondary amine functionality include, without limitation,
diethylene triamine, triaminoalkanes (C.sub.8, C.sub.9, C.sub.10
etc. all primary, various isomers), isophorone diamine, and
1,4-diaminocyclohexane.
[0042] Examples of suitable oligomers having primary and/or
secondary amine functionality are triethylenetetramine, methylene
dianiline oligomers (MDA oligomers), and dendrimeric compounds made
from reacting protected diethylene triamine with isocyanurates
followed by removing the protection. Examples of suitable polymers
include, without limitation, primary and/or secondary
amine-functional acrylic polymers. The amine-functional polymer
preferably has an equivalent weight from about 300 to about 1500.
The acrylic polymer may be produced by copolymerizing an
appropriate amount of a primary and/or secondary amine
group-containing monomer(s) with one or more further addition
polymerizable monomers.
[0043] Examples of suitable hydroxyl-functional crosslinkers (c)
include, without limitation, triols like glycerols, tetrols like
pentaerythritols, hydroxy functional acrylic polymers.
[0044] In a third embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and silyl
ether functionality, (b) a material having secondary hydroxyl
functionality, and (c) a crosslinker having primary hydroxyl
functionality.
[0045] Compounds (a) having isocyanate functionality and silyl
ether functionality have already been described.
[0046] The material (b) having secondary hydroxyl functionality may
be a compound, an oligomer, or a polymer having at least one,
preferably a plurality of such secondary hydroxyl groups. Examples
of compounds having secondary hydroxyl groups include, without
limitation, 2,3-butanediol, 2,3-pentanediol, 2,4-pentanediol,
2,3,4-pentanetriol, 2,3,4- and 2,3,5-hexanetriols.
[0047] Examples of suitable oligomers having secondary hydroxyl
functionality are mono-, di-, tri-, and tetra-saccharides. Examples
of suitable polymers include, without limitation, secondary
hydroxyl-functional acrylic polymers made with hydroxypropyl
acrylate or methacrylate. The secondary hydroxyl-functional polymer
preferably has an equivalent weight from about 300 to about 1500.
The acrylic polymer may be produced by copolymerizing an
appropriate amount of secondary hydroxyl group-containing
monomer(s), for example by copolymerizing with one or more monomers
such as methyl methacrylate, butyl methacrylate, and styrene.
[0048] Examples of suitable primary hydroxyl-functional
crosslinkers (c) include, without limitation, pentaerythritol, star
polyester polyols, dendrimeric polyols from dimethylolpropionic
acid or from trimethylolpropane, and dimethylolpropionic acid.
[0049] In a fourth embodiment, the curable coating composition
comprises (a) a compound having hydroxyl or amino functionality and
silyl ether functionality, (b) a material having isocyanate
functionality, and (c) a crosslinker having hydroxyl
functionality.
[0050] Compounds (a) having hydroxyl or amino functionality and
silyl ether functionality include, without limitation,
bis(2-hydroxyethyl)-3-aminopropyl-triethoxysilane,
hydroxymethyltriethoxysilane, 4-aminobutyltriethoxysilane,
3-aminopropyltrimethoxysilane,
N-(2-aminoethyl)3-aminopropylmethyl-dimethoxysilane, and
aminophenyltrimethoxysilane,
[0051] The material (b) having isocyanate functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of isocyanate groups. Examples of compounds and
oligomers having isocyanate groups include, without limitation,
diisocyanates such as hexamethylene diisocyanate and isophorone
diisocyanates; isocyanurates, biurets, allophanates, and uretdiones
of diisocyanates, and isocyanate-functional prepolymers such as the
reaction product of one mole of a triol with three moles of a
diisocyanate.
[0052] Examples of suitable polymers include, without limitation,
isocyanate-functional acrylic polymers made by copolymerizing
isocyanate-containing acrylate or methacrylate monomers like
2-isocyanatomethylmethacrylate, 2-isocyanatoethylmethacrylate or
benzene, 1-(1-isocyanato-1-methyl ethyl)-4-1-methyl ethynyl)) or
commonly known as meta TMI with other comonomers such as
methylmethacrylate, styrene, butylmethacrylate. The
isocyanate-functional polymer preferably has an equivalent weight
from about 300 to about 1500.
[0053] Examples of suitable hydroxyl-functional crosslinkers (c)
include, without limitation, ethylene glycol, glycerin,
pentaerythritol, hydroxy functional acrylic polymers, polyester
polyols, and polyurethane polyols.
[0054] In a fifth embodiment, the curable coating composition
comprises (a) a compound having epoxide functionality and carbamate
functionality, (b) a material having carboxylic acid functionality,
and (c) an aminoplast crosslinker.
[0055] Compounds (a) having epoxide functionality and carbamate
functionality include, without limitation, the epoxide of
hydroxypropylcarbamate acrylate monomer or epoxide of
hydroxyethylcarbamate acrylate monomer. These compounds may be
prepared by reacting epichlorohydrin with hydroxypropyl carbamate.
They can also be prepared by epoxidizing hydroxypropylcarbamate
acrylate monomer or hydroxyethylcarbamate acrylate monomer.
[0056] The material (b) having carboxylic functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of carboxylic acid groups. Examples of compounds having
carboxylic acid functionality include, without limitation, hexanoic
acid, 2-hydroxystearic acid, hexahydrophthalic acid, succinic acid,
and glutaric acid.
[0057] Examples of suitable oligomers and polymers include, without
limitation, branched polyester carboxylic acids and carboxylic
acid-functional acrylic polymers. The carboxylic acid-functional
polymer preferably has an equivalent weight from about 300 to about
1500. Oligomers can be made by reacting branched alcohols (simple
to hyperbranched) with suitable anhydrides. The acrylic polymer may
be produced by copolymerizing an appropriate amount of an
ethylenically unsaturated carboxylic acid compound, for example by
copolymerizing one or more of the monomers acrylic acid,
methacrylic acid, crotonic acid, maleic acid (or maleic anhydride,
followed by hydrolysis of the anhydride to the acid).
[0058] Aminoplast crosslinkers have already been described.
[0059] In a sixth embodiment, the curable coating composition
comprises (a) a compound having alkoxyalkyl amino functionality and
carbamate functionality, (b) a material having hydroxyl
functionality, and (c) an aminoplast crosslinker.
[0060] Compounds (a) having alkoxyalkyl amino functionality and
carbamate functionality include, without limitation, partially
defunctionalized aminoplasts. These compounds may be prepared by
reacting aminoplasts with less than equivalent amounts of alkyl
carbamates.
[0061] The material (b) having hydroxyl functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of hydroxyl groups. Examples of compounds having
hydroxyl functionality include, without limitation, glycols,
glycerols, pentaerythritol, dulcitols, starch, and so on.
[0062] Examples of suitable oligomers and polymers include, without
limitation, hydroxyl-functional acrylic polymers. The
hydroxyl-functional polymer preferably has an equivalent weight
from about 300 to about 1500. The acrylic polymer may be produced
by copolymerizing an appropriate amount of a hydroxyl-containing
ethylenically unsaturated monomer, for example by copolymerizing
one or more of the monomers hydroxyethyl acrylate, hydroxyethyl
methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
hydroxybutyl acrylate, and hydroxybutyl methacrylate.
[0063] Aminoplast crosslinkers have already been described.
[0064] In a seventh embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and
carbamate functionality, (b) a material having hydroxyl
functionality, and (c) an aminoplast crosslinker.
[0065] Compounds (a) having isocyanate functionality and carbamate
functionality include, without limitation, diisocyanates,
triisocyanurates, or acrylic polymers with a number of isocyanate
groups in which a portion but not all of the isocyanate groups have
been reacted with an hydroxy carbamate like hydroxypropyl
carbamates. An acrylic polymer having both isocyanate and primary
carbamate can be made by using appropriate isocyanate- and primary
carbamate-functional monomers and polymerizing them with suitable
non-functional monomers.
[0066] The material (b) having hydroxyl functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of hydroxyl groups, as described above.
[0067] Aminoplast crosslinkers have already been described.
[0068] In an eighth embodiment, the curable coating composition
comprises (a) a compound having isocyanate functionality and
ethylenic unsaturation, (b) a material having hydroxyl
functionality, and (c) an ethylenically unsaturated crosslinker
with a photocatalyst. This composition cures with heat and actinic
radiation.
[0069] Compounds (a) having isocyanate functionality and ethylenic
unsaturation include, without limitation,
2-isocyanatomethylmethacrylate, 2-isocyanatoethylmethacrylate, and
benzene, 1-(1-isocyanato-1-methyl ethyl)-4-1-methyl ethynyl))
(commonly known as meta TMI).
[0070] The material (b) having hydroxyl functionality may be a
compound, an oligomer, or a polymer having at least one, preferably
a plurality of hydroxyl groups, as described above.
[0071] Suitable examples ethylenically unsaturated crosslinkers
include, without limitation, trimethylolpropane triacrylate,
pentaerythritol tetraacrylate, and pentaerythritol tetra
methacrylate.
[0072] Suitable examples of photoinitiators include, without
limitation, benzoin ethers, benzyl ketals, dialkoxy acetophenones,
hydroxyalkyl phenones, amino, alkyl phenones, benzophenone/amines,
thioxanthones/amines, and titanocenes.
[0073] The coating compositions of the eighth embodiment are cured
with a combination of heat and actinic radiation. Examples of
suitable actinic radiation include ultraviolet radiation and
electron beam radiation.
[0074] Clearcoat compositions of the invention are formulated
without pigments. Pigmented coating compositions of the invention
may contain pigments and fillers in amounts typically of up to
about 40% by weight, based on total weight of the coating
composition. The pigments used may be inorganic pigments, including
metal oxides, chromates, molybdates, phosphates, and silicates.
Examples of inorganic pigments and fillers that could be employed
are titanium dioxide, barium sulfate, carbon black, ocher, sienna,
umber, hematite, limonite, red iron oxide, transparent red iron
oxide, black iron oxide, brown iron oxide, chromium oxide green,
strontium chromate, zinc phosphate, silicas such as fumed silica,
calcium carbonate, talc, barytes, ferric ammonium ferrocyanide
(Prussian blue), ultramarine, lead chromate, lead molybdate, and
mica flake pigments. Organic pigments may also be used. Examples of
useful organic pigments are metallized and non-metallized azo reds,
quinacridone reds and violets, perylene reds, copper phthalocyanine
blues and greens, carbazole violet, monoarylide and diarylide
yellows, benzimidazolone yellows, tolyl orange, naphthol orange,
and the like.
[0075] The coating composition may include a catalyst to enhance
the cure reaction. Such catalysts are well-known in the art and
include, without limitation, zinc salts, tin salts, blocked
para-toluenesulfonic acid, blocked dinonylnaphthalenesulfonic acid,
or phenyl acid phosphate.
[0076] A solvent or solvents may be included in the coating
composition. In general, the solvent can be any organic solvent
and/or water. In one preferred embodiment, the solvent includes a
polar organic solvent. More preferably, the solvent includes one or
more organic solvents selected from polar aliphatic solvents or
polar aromatic solvents. Still more preferably, the solvent
includes a ketone, ester, acetate, or a combination of any of
these. Examples of useful solvents include, without limitation,
methyl ethyl ketone, methyl isobutyl ketone, n-amyl acetate,
ethylene glycol butyl ether-acetate, propylene glycol monomethyl
ether acetate, xylene, N-methylpyrrolidone, blends of aromatic
hydrocarbons, and mixtures of these. In another preferred
embodiment, the solvent is water or a mixture of water with small
amounts of co-solvents. In general, protic solvents such as alcohol
and glycol ethers are avoided when the coating composition includes
the optional polyisocyanate crosslinker, although small amounts of
protic solvents can be used even though it may be expected that
some reaction with the isocyanate groups may take place during
curing of the coating.
[0077] Additional agents, for example hindered amine light
stabilizers, ultraviolet light absorbers, anti-oxidants,
surfactants, stabilizers, wetting agents, rheology control agents,
dispersing agents, adhesion promoters, etc. may be incorporated
into the coating composition. Such additives are well-known and may
be included in amounts typically used for coating compositions.
[0078] The coating compositions can be coated on a substrate by
spray coating. Electrostatic spraying is a preferred method. The
coating composition can be applied in one or more passes to provide
a film thickness after cure of typically from about 20 to about 100
microns.
[0079] The coating composition can be applied onto many different
types of substrates, including metal substrates such as bare steel,
phosphated steel, galvanized steel, or aluminum; and non-metallic
substrates, such as plastics and composites. The substrate may also
be any of these materials having upon it already a layer of another
coating, such as a layer of an electrodeposited primer, primer
surfacer, and/or basecoat, cured or uncured.
[0080] After application of the coating composition to the
substrate, the coating is cured, preferably by heating at a
temperature and for a length of time sufficient to cause the
reactants to form an insoluble polymeric network. The cure
temperature is usually from about 105.degree. C. to about
175.degree. C., and the length of cure is usually about 15 minutes
to about 60 minutes. Preferably, the coating is cured at about
120.degree. C. to about 150.degree. C. for about 20 to about 30
minutes. Heating can be done in infrared and/or convection ovens.
Curable compositions containing ethylenically unsaturated materials
are cured by a step including exposure to actinic radiation.
[0081] In one embodiment, the coating composition is utilized as
the clearcoat of an automotive composite color-plus-clear coating.
The pigmented basecoat composition over which it is applied may be
any of a number of types well-known in the art, and does not
require explanation in detail herein. Polymers known in the art to
be useful in basecoat compositions include acrylics, vinyls,
polyurethanes, polycarbonates, polyesters, alkyds, and
polysiloxanes. Preferred polymers include acrylics and
polyurethanes. In one preferred embodiment of the invention, the
basecoat composition also utilizes a carbamate-functional acrylic
polymer. Basecoat polymers may be thermoplastic, but are preferably
crosslinkable and comprise one or more type of crosslinkable
functional groups. Such groups include, for example, hydroxy,
isocyanate, amine, epoxy, acrylate, vinyl, silane, and acetoacetate
groups. These groups may be masked or blocked in such a way so that
they are unblocked and available for the crosslinking reaction
under the desired curing conditions, generally elevated
temperatures. Useful crosslinkable functional groups include
hydroxy, epoxy, acid, anhydride, silane, and acetoacetate groups.
Preferred crosslinkable functional groups include hydroxy
functional groups and amino functional groups.
[0082] Basecoat polymers may be self-crosslinkable, or may require
a separate crosslinking agent that is reactive with the functional
groups of the polymer. When the polymer comprises hydroxy
functional groups, for example, the crosslinking agent may be an
aminoplast resin, isocyanate and blocked isocyanates (including
isocyanurates), and acid or anhydride functional crosslinking
agents.
[0083] The clearcoat coating composition of this invention is
generally applied wet-on-wet over a basecoat coating composition as
is widely done in the industry. The coating compositions described
herein are preferably subjected to conditions so as to cure the
coating layers as described above.
[0084] The invention is further described in the following
examples. The examples are merely illustrative and do not in any
way limit the scope of the invention as described and claimed. All
parts are parts by weight unless otherwise noted. The examples are
prophetic.
EXAMPLES
Synthesis I. Synthesis of an Acid Carbamate Molecule (Compound
1)
[0085] A mixture of 308 g of hexahydrophthalic anhydride and 238 g
of hydroxypropyl carbamate in 103 g of n-butyl acetate is held at
100-110.degree. C. until infrared spectroscopy shows no trace of
anhydride and titration shows that the equivalent weight is 260-275
g/COOH. Total time for the reaction to be complete is 12 hours. At
the end of twelve hours, the product (Compound 1) has a
non-volatiles of 77.6% by weight and an equivalent weight of 274.9
g/COOH.
Synthesis II. Synthesis of an Acid Carbamate Molecule (Compound
2)
[0086] A mixture of 200 g of succinic anhydride and 119 g of
hydroxypropyl carbamate in 100 g of toluene is held at
100-110.degree. C. until infrared spectroscopy shows no trace of
anhydride and titration shows that the equivalent weight is 210-230
g/equiv. COOH. Total time for the reaction to be complete is 12
hours. At the end of twelve hours, the product (Compound 2) has a
non-volatiles of 81% by weight and an equivalent weight of 213
g/COOH.
Synthesis III. Synthesis of Compound with Epoxide and Carbamate
Functional Groups (Compound 3)
[0087] A mixture of 92 g of epichlorohydrin and 50 g of xylene is
slowly added to 120 g hydroxypropyl carbamate in 60 g of xylene
kept at 90.degree. C. in a reactor. The reactor is swept
continuously by a stream of dry nitrogen exiting through a
condenser, the top of which is connected to a running water trap to
capture the side product HCl. After the addition, the heating and
nitrogen sweep are continued for one hour. Check of the water trap
at the end of the reaction period shows no more production of HCl.
The final solution (Compound 3) is 61% by weight nonvolatiles with
an equivalent weights of 175 g/epoxide and carbamate (each) on
solids.
Synthesis IV. Synthesis of Aminoplast Partially Functionalized with
Carbamate Groups (Compound 4)
[0088] 700 g of Cymel 300 (hexamethoxymethyl melamine, HMMM) is
mixed with 250 g of methyl carbamate, 400 g of methanol, and 0.5 g
of p-toluene sulfonic acid. The mixture is heated to 65.degree. C.
After 50 hours, it is calculated from the amount of methyl
carbamate still present (determined by gas chromatography), that
25% of the reactive alkoxy groups on the aminoplast have been
replaced with carbamate functionalities. Calculated equivalents
weights are 117 g/methoxy and 352 g/carbamate.
Synthesis V. Synthesis of Compound with Isocyanate and Carbamate
Groups (Compound 5)
[0089] 198 g of Desmodur.RTM. 3390 N is reacted with 40 g of
hydroxypropyl carbamate in 100 g of xylene at 80.degree. C., with
0.1 g of dibutyl tin dilaurate catalyst. When the titrated value of
% NCO of the reaction mixture stalls (at about 66% of its original
value) the reaction is done. The product (Compound 5) has a
non-volatile content of 70% and equivalent weights of 325 g/NCO and
654 g/carbamate on solids.
Synthesis VI. Synthesis of Compound with Isocyanate and Ethylenic
Unsaturation (Compound 6)
[0090] To a solution of 178 g of Desmodur.RTM. 3300 (HDI
triisocyanurate) in 100 g aromatic 100 kept at 70.degree. C. and
under a blanket of oxygen, is added 77 g of 2-hydroxyethyl acrylate
and 0.01 g of dibutyl tin dilaurate over 30 minutes. The reactor is
held at 70.degree. C. until titration for % NCO shows a decrease in
value of about 66% and the decrease stalls. The resulting solution
(Compound 6) is 72% by weight nonvolatiles and has equivalent
weights of 255 g/isocyanate and 128 g/carbon-carbon double bond on
solids.
Synthesis VII. Synthesis of Epoxy-Functional Acrylic Polymer
(Polymer 1)
[0091] A mixture of acrylic monomers glycidyl methacrylate 99.4 g,
n-butyl acrylate 40.6 g, butyl methacrylate 60 g in aromatic 100 10
g and a mixture of tert.-butyl peroxy 2-ethylhexanoate 20 g in 10 g
aromatic 100 are co-metered into a reaction vessel containing 60 g
of aromatic 100 kept at 140.degree. C. in four hours. After the
four hour add, an additional 2 g of tert.-butyl peroxy
2-ethylhexanoate in 10 g of aromatic 100 is metered in over 30
minutes to complete the polymerization. After a hold period of 1
hour, the reaction mixture is cooled for storing. Measured solids
are 70% by weight nonvolatiles, equivalent weight is 300 g/epoxy,
and a molecular weight measured by gel permeation chromatography
against polystyrene standard shows M.sub.n 745, M.sub.w 1400 and
polydispersity 1.9. Calculated T.sub.g (by the Fox equation) of the
resin is 23.degree. C.
Synthesis VIII. Synthesis of Hydroxy-Functional Acrylic Polymer
(Polymer 2)
[0092] A mixture of 12.4 g acrylic acid, 48.2 g of 2-hydroxyethyl
methacrylate, 16.6 g of 2-ethylhexyl acrylate, 8 g of styrene, 42 g
of n-butyl methacrylate, and 7.4 g of methyl methacrylate is added
over four hours simultaneously with a solution of 12.4 g of
tert-butyl peroxy 2-ethylhexanoate and 6 g of tert-butyl peroxy
acetate in 2 g of propylene glycol monopropyl ether to 25 g of
propylene glycol monopropyl ether in a reactor at 150.degree. C.
After the addition, the product is maintained at 140.degree. C. for
an additional hour to complete the conversion. Then, 30 g of methyl
propyl ketone is added to bring the resin to a 65% by weight
non-volatile solution. Theoretical T.sub.g was calculated by the
Fox equation to be 23.4.degree. C. Equivalent weight is 330
g/hydroxyl and molecular weight is M.sub.n 3300, M.sub.w 5850 and
polydispersity 1.8 (by GPC using polystyrene standard).
Synthesis IX. Synthesis of Hydroxy-Functional Acrylic Polymer
(Polymer 3)
[0093] A mixture of 12.4 g acrylic acid, 52.2 g of 2-hydroxypropyl
methacrylate, 16.6 g of 2-ethylhexyl acrylate, 8 g of styrene, 42 g
of n-butyl methacrylate and 7.4 g of methyl methacrylate is added
over 4 hours simultaneously with a solution of 12.4 g of tert-butyl
peroxy 2-ethylhexanoate and 6 g of tert.-butyl peroxy acetate in 2
g of propylene glycol monopropyl ether to 28 g of propylene glycol
monopropyl ether in a reactor at 150.degree. C. After the addition,
the product is maintained at 140.degree. C. for an additional hour
to complete the conversion. Then, 32 g of methyl propyl ketone is
added to bring the resin to a 65% non-volatile solution.
Theoretical T.sub.g is calculated (by Fox equation) to be
23.4.degree. C., measured equivalent weight of 330 g/hydroxyl, and
a GPC molecular weight of M.sub.n 3300, M.sub.w 5850 and
polydispersity 1.8. Since 2-hydroxypropyl methacrylate is a mixture
of 80% secondary and 20% primary hydroxyls, calculated equivalent
weights are 412 g/secondary hydroxyl and 1650 g/primary
hydroxyl.
Synthesis X. Synthesis of Isocyanate-Functional Acrylic Polymer
with Trimethoxysilyl Groups (Polymer 4)
[0094] To 750 g of amyl acetate at 110.degree. C. in a reactor, add
simultaneously over three hours a mixture of 750 g of 2-ethylhexyl
acrylate, 550 g of cyclohexyl methacrylate, 28 g of styrene, 80 g
of trimethoxysilylpropyl methacrylate, 120 g 2-isocyanatoethyl
methacrylate in 50 g amyl acetate and 4 g of Vazo.RTM.-67 in 100 g
of aromatic 100. After the addition, the reaction mixture is held
at 110.degree. C. for two hours to complete the reaction. The resin
has a final solids of 65% by weight nonvolatiles with equivalent
weights of 1973 g/NCO and 1580 g/methoxy from the trimethylsilyl
group.
Synthesis XI. Synthesis of Isocyanate-Functional Acrylic Polymer
(Polymer 5)
[0095] To 750 g of amyl acetate at 110.degree. C. in a reactor, add
simultaneously over three hours a mixture of 790 g of 2-ethylhexyl
acrylate, 590 g of cyclohexyl methacrylate, 28 g of styrene, 120 g
2-isocyanatoethyl methacrylate in 50 g amyl acetate and 4 g of
Vazo.RTM.-67 in 100 g of aromatic 100. After the addition, the
reaction mixture is held at 110.degree. C. for two hours to
complete the reaction. The resin has a final solids of 65% by
weight nonvolatiles with equivalent weight of 1973 g/NCO.
Synthesis XII. Synthesis of Carboxylic Acid-Functional Acrylic
Polymer (Polymer 6)
[0096] To 750 g of amyl acetate at 110.degree. C. in a reactor, add
simultaneously over three hours a mixture of 750 g of 2-ethylhexyl
acrylate, 550 g of cyclohexyl methacrylate, 28 g of styrene, 80 g
of acrylic acid, 120 g n-butyl methacrylate in 50 g amyl acetate
and 4 g of Vazo.RTM.-67 in 100 g of aromatic 100. After the
addition, the reaction mixture is held at 110.degree. C. for two
hours to complete the reaction. The resin has a final solids of 65%
by weight nonvolatiles with equivalent weights of 1375 g/COOH.
Synthesis XII. Synthesis of Carboxylic Acid-Functional Polyester
Polymer (Polymer 7)
[0097] A combination of 136 g of pentaerythrytol and 616 g of
hexahydrophthalic anhydride is loaded in a reactor at 70.degree. C.
and heated to 110.degree. C. After holding at 110.degree. C. for 1
hour, the temperature is slowly increased to 120.degree. C. Any
exotherm observed is controlled by cooling so the reaction does not
go above 140.degree. C. The reactor is held at 120-125.degree. C.
infrared spectroscopy shows absence of anhydride peaks. 200 g of
xylene is added to make a resin solution at about 80% by weight
non-volatiles and an equivalent weight of 188 g/carboxylic acid on
solids.
Synthesis XIII. Synthesis of Isocyanate- and Carbamate-Functional
Acrylic Polymer (Polymer 8)
[0098] To 750 g of amyl acetate at 110.degree. C. in a reactor, add
simultaneously over three hours a mixture of 750 g of 2-ethyl,hexyl
acrylate, 550 g of cyclohexyl methacrylate, 28 g of styrene, 80 g
of carbamate propyl acrylate, and 120 g 2-isocyanatoethyl
methacrylate in 50 g amyl acetate and 4 g of Vazo.RTM.-67 in 100 g
of aromatic 100. After the addition, the reaction mixture is held
at 110.degree. C. for two hours to complete the reaction. The resin
has a final solids of 65% by weight nonvolatiles with equivalent
weights of 1973 g/NCO and 3304 g/carbamate.
Coating Composition Examples 1-18
[0099] Thermoset clearcoat coating compositions according to the
invention are prepared by combining the materials indicated in the
tables that follow.
Examples of Embodiment 1
Groups --COOH and --OCONH.sub.2, Epoxide, Aminoplasts
[0100] TABLE-US-00001 Example Example Example Example INGREDIENT 1,
g 2, g 3, g 4, g Polymer 1 100 100 100 TGIC 100 Compound 1 80 63.8
135 Compound 2 62 Neodecanoic acid 16.2 86 Resimine BM-9539.sup.1
6.0 Cymel 327.sup.2 32 32 25.6 52 Additives Package.sup.3 15.5 15.5
15.5 15.5 Exxate 1000 1.0 1.0 1.0 1.0 Methyl propyl ketone 1.0 1.0
1.0 1.0 Total 229.5 211.5 283.1 390.5
Examples of Embodiment 2
Groups --NCO and --Si(--OR.sub.3), --NHR, --OH
[0101] TABLE-US-00002 INGREDIENTS Example 5, g Example 6, g
Isocyanatopropyl trimethoxy silane.sup.5 102 Polymer 4 303
Cyclohexane 1,4-diamine 58 Tris(2-aminoethyl)amine 5 Polymer 2 700
50 Additive package.sup.3 15.5 15.5 Exxate 1000 50 10
Examples of Embodiment 3
Groups --NCO and --Si(--OR.sub.3)--OH (Primary and Secondary
[0102] TABLE-US-00003 INGREDIENTS Example 7, g Example 8, g
Isocyanatopropyl trimethoxy silane.sup.5 102 102 Polymer 2 170
Pentaerythritol 17 Polymer 3 600 600 Additive package.sup.3 15.5
15.5 Exxate 1000 50 10
Examples of Embodiment 4
Groups --OH and --Si(--OR).sub.3, --NCO, --OH
[0103] TABLE-US-00004 INGREDIENTS Example 9, g Example 10, g
Hydroxymethyl, triethoxysilane 19 4-aminobutyl, triethoxysilane 24
Polymer 5 304 pentaerythritol 10 Polymer 2 150 Additive
package.sup.3 15.5 15.5 Exxate 1000 50 10
Examples of Embodiment 5
Groups Epoxide and --OCONH.sub.2, --COOH Aminoplasts
[0104] TABLE-US-00005 INGREDIENTS Example 11, g Example 12, g
Compound 3 17 17 Polymer 6 137 Polymer 7 23.5 Cymel 327.sup.2 10 10
Additive package.sup.3 15.5 15.5 Exxate 1000 50 10
Examples of Embodiment 6
Groups RO--R.sub.2--NH-- and --OCONHR.sub.3, --OH, Aminoplasts
[0105] TABLE-US-00006 INGREDIENTS Example 13, g Example 14, g
Compound 4 117 117 Polymer 2 507 pentaerythritol 34 Cymel 327.sup.2
26 26 Additive package.sup.3 15.5 15.5 Exxate 1000 50 10
Examples of Embodiment 7
Groups --NCO and --OCONH.sub.2, --OH, Aminoplasts
[0106] TABLE-US-00007 INGREDIENTS Example 15, g Example 16, g
Compound 5 32.5 Polymer 8 190 Pentaerythritol 17 Cymel 327.sup.2 40
40 Polymer 2 52 Additive package.sup.3 15.5 15.5 Exxate 1000 50
10
Examples of Embodiment 8
Groups --NCO and --C.dbd.C--, --OH, --C.dbd.C--
[0107] This is a case of dual cure (thermal and actinic) which can
be done simultaneously or in stages of thermal followed by actinic
radiation. Other way around of actinic radiation followed by
thermal is not preferred as the first cure results in high
viscosity resin reducing mobility for further reaction.
TABLE-US-00008 INGREDIENTS Example 17, g Example 18, g
3-isocyanatopropyl acrylate 16 g Compound 6 70 Pentaerythritol 6.8
Polymer 2 51 Pentaerythritol tetraacrylate 35 35 Additive
package.sup.4 15.5 15.5 Exxate 1000 50 10 .sup.1Resimene BM-9539 is
available from UCB Surface Specialties .sup.2CYMEL 327 is available
from Cytec Industries. .sup.3The additives package included light
stabilizers, rheology control agents, a strong acid catalyst,
leveling agents, and solvent. .sup.4The additive package included
photoinitiators along with the usual additives. .sup.5obtained from
Osi Specialties, under the trade name Silquest A-link 35 silane
[0108] Examples 1-18 can each be applied to a substrate, for
example by atomized spray, in a layer then cured to produce a clear
coating layer. The coating layers have good optical properties
(e.g., DOI, clarity, gloss) and film properties (e.g., good cure,
scratch and mar resistance, and etch resistance).
[0109] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *